1. Field of the Invention
The present invention relates to an intra-subject position display system for displaying a position of an intra-subject device, which is introduced into a subject and moves inside the subject.
2. Description of the Related Art
Recently, in the field of endoscopy, there has been suggested a swalloable capsule type endoscope. The capsule type endoscope is provided with an imaging function and a radio communication function. The capsule type endoscope has a function of moving inside the body cavity (for example, inside a stomach, small intestine, or other organs) by the organ's peristaltic motion and taking images sequentially after being swallowed from the mouth of the subject for observation (examination) until it is excreted naturally.
While it moves inside the body cavity, image data picked up in the subject by the capsule type endoscope is sequentially transmitted to the outside by radio communication and then stored in an external memory. The subject such as a patient can act freely after swallowing the capsule type endoscope until it is excreted, by carrying a receiver having the radio communication and memory functions. After the capsule type endoscope is excreted, a doctor or a nurse can output images of the organ to a display on the basis of the image data stored in the memory for a diagnosis.
In this type of capsule type endoscope, there has been suggested a system comprising a receiver with a function of detecting a position of a capsule type endoscope in the subject, for example, in order to pick up endoscopic images of a specific organ inside the subject. As an example of the capsule endoscopic system having this type of position detecting function, there has already been known one in which a radio communication function built in the capsule type endoscope is also used for a positional detection.
For example, in a capsule endoscopic system disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 2003-19111, a receiver provided outside the subject has a plurality of antenna elements and receives a radio signal transmitted from a capsule type endoscope with the individual antenna elements. The foregoing capsule endoscopic system detects a position of the capsule type endoscope in the subject on the basis of differences of reception intensity in the individual antenna elements.
In the conventional capsule endoscopic system, however, it is hard for a doctor, a nurse, or the like to understand the picked-up image's position in the subject. This problem will be described hereinafter.
In the conventional capsule endoscopic system, the position of the capsule type endoscope is detected on the basis of differences of reception intensity in the plurality of antenna elements provided in the receiver in response to the radio signal transmitted from the capsule type endoscope. When this arrangement is adopted, however, it is possible to detect the position of the capsule type endoscope in relation to the receiver, but it is hard to detect a relative position of the capsule type endoscope in the subject.
A subject has individual variations depending on the build of the subject's body, for example, according to sex, age, race or the like. If only the position of the capsule type endoscope relative to the receiver (so to speak, an absolute position) is derived, it is hard for a doctor or nurse to realize where the capsule type endoscope locates within the subject based on the absolute position. Therefore, it is hard to determine in which organ of the subject the capsule type endoscope positions at a given time. In other words, a position detecting mechanism in the conventional capsule endoscopic system is only capable of teaching an absolute position such as the position of the capsule type endoscope in relation to the receiver. In some cases, such a system does not fully contribute to improve a convenience on a diagnosis or the like.
This invention aims to provide an intra-subject position display system enabling an operator such as a doctor to easily recognize a relative position relationship between a subject and an intra-subject device such as a capsule type endoscope introduced into the subject.